1. Field of the Invention
This invention relates to electrical connectors. More specifically, this invention relates to electrical connectors, preferably coaxial electrical connectors that are rigidly mounted but need to move slightly relative to the mounting to achieve correct alignment with a corresponding mating connector. The invention also relates to sensitive coaxial electrical connectors that must be mounted to a circuit board or other type of electronic equipment, but which can be damaged during soldering or other processing steps that occur when the circuit board or equipment is manufactured.
2. Description of Related Art
Coaxial connectors are widely used to carry signals between different circuits in electronic devices and between different electronic modules in complex modularly designed equipment. In a common design, one member of a mating pair of coaxial connectors is soldered directly to a printed circuit board, carrying a first circuit, and the other member of the pair is attached to a length of coaxial cable. The coaxial cable is attached to a second circuit board, and the connectors are mated by hand. The flexibility of the coaxial cable avoids alignment problems between the two connectors or the circuit boards.
However, the cables needed for this type of design take more space than is desirable. As the number of connections to be made increases, it has become desirable to eliminate the cable and attach the two mating connectors directly to their respective circuit boards or electronic modules to permit direct connection between them.
One difficulty with directly mounting the connectors is that conventional connectors are rigid which results in alignment difficulties and undesirable stresses on the circuit boards and connectors. Mounting tolerances can add up to the point where proper connection is not possible. Even if the connectors can be mounted accurately to their respective circuit boards, it can be difficult to get the connectors to mate. Conventional single piece coaxial connectors that are rigidly soldered to a printed circuit board are not well suited to this type of application. The problem is compounded where the connectors are positioned at the back of a circuit board or piece of electronic equipment where they cannot be seen and must be mated blind.
A related problem is where multiple coaxial connectors are to be mounted near each other on a single circuit board. In this situation, it is desirable to place a housing around all the adjacent connectors and provide a corresponding mating housing around the mating connectors. This allows all the connectors to be mated at once. This design may be used even where the mating connectors are to be attached to flexible coaxial cable. However, minor positioning errors and tolerances can add up for the connectors that are rigidly mounted to the circuit board making it very difficult to engage all of the connectors in the mating housing.
To address these problems, self aligning coaxial connectors have been developed. One type of self aligning connector has one end that is rigidly soldered to the printed circuit (PC) board and another end that moves relative to the soldered end. U.S. Pat. No. 5,769,652 shows an example of this type of connector. The connector shown therein has a first piece that is rigidly mounted to the circuit board and a second piece that is captured by and floats relative to the first piece. The first piece is assembled to the second piece when the connector is manufactured. Electrically conductive springs or flexible members are used to electrically connect the two pieces together.
A difficulty with this type of connector is that the connector is installed fully assembled and is therefore exposed to all processing steps that the circuit board is subjected to, including heat, during the soldering step, and various solvents and chemicals during cleaning steps. Some coaxial connectors, particularly high performance connectors, can be damaged during conventional printed circuit board processing steps.
Another type of self-aligning connector is not attached rigidly to the circuit board or electronic module. Instead, the connector floats in an oversized opening in the PC board or module case with flanges on each side of the circuit board or case to retain it in the opening. This allows the connector to move within the opening so that it can easily align with a mating connector. U.S. Pat. Nos. 4,580,862 and 4,358,174 show examples of this type of connector. These connectors provide the desired self-alignment capability and they can be installed after the circuit board processing is complete, but they cannot be directly soldered to the circuit board, and therefore require additional soldering steps to install.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide an electrical connector that is rigidly mounted and yet moves sufficiently to align with a corresponding electrical connector.
Another object of the present invention is to provide an electrical connector that can be soldered to a circuit board during the normal circuit board soldering steps without risk of damaging the sensitive portions of the connector during the soldering or related manufacturing steps.
A further object of the present invention is to provide a connector that accommodates axial insertion distance errors, radial position alignment errors and angular alignment errors.
Yet another object of the present invention is to provide an electrical connector that has a first part that may be installed permanently during construction of a circuit and a second part that may be varied and installed after construction of the circuit to accommodate different types of mating connectors.
A further object of the present invention is to provide an electrical connector that may be installed in a shell or housing.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.